The Sony a9 camera packs an incredible autofocus system, full-frame image sensor, and 4K video, all in a body that's smaller than most SLRs.

Photographers shooting demanding subjects—auto racing, sailing, sports, wildlife, and the like—have long been limited to using the highest of high-end SLRs in order to capture fast action. Full-frame bodies like the Nikon D5 and Canon EOS-1D X Mark II shoot at a blistering rate and track subjects with aplomb, but are heavy and priced in the $6,000 range. Sony's full-frame mirrorless system has proven to be a formidable option for photographers whose needs fall shy of capturing the fastest action. With the new a9 ($4,499.99), sports shooters have a body that meets their demanding needs. Using a stacked sensor design, the camera captures at 20fps using an electronic shutter, without any sort of blackout during exposure—so you can keep tracking moving targets. Its performance in real life lives up to the promises on paper, so we're naming the a9 our Editors' Choice.

Design

The a9 looks a lot like the full-frame bodies in the a7 II family at a glance. Its body isn't that far off in size—it measures 3.9 by 5.0 by 2.5 inches (HWD) and weighs 1.5 pounds without a lens. There are a few physical differences on the body itself—an extra control dial to the left of the EVF, a touch screen, and a dedicated joystick to select a focus point being the most noticeable.

The body itself is protected from dust and moisture. I've not had an opportunity to shoot with the a9 in bad weather, but I have used a7 II models in rough conditions and they've performed quite well. It will take a teardown to see just how well the a9 is sealed, but given its price point and target audience, I hope Sony delivers protection that's at least as good as you get with a7 cameras.

Sensor resolution is 24MP, which is plenty for most applications, but sounds paltry when you know that Sony also makes a 42MP full-frame image sensor. But while the 42MP sensor used in the a7R II, a99 II, and RX1R II delivers fantastic image quality, it doesn't offer as much speed as the a9's stacked CMOS design, which, in very basic terms, improves readout speed by putting RAM right on the image sensor. Like the 42MP sensor, the a9's 24MP chip features a BSI design, so it has an advantage over the a7 II at high ISO settings. The a7 II tops out at ISO 25600, but you can push the a9 to ISO 204800.

The Alpha 9 includes a command dial on its front handgrip, along with the power switch and shutter release at an angle at its top. On the top plate itself you'll find programmable C1 and C2 buttons behind the shutter, along with an EV compensation dial (with settings from -3 to +3 EV in third-stop increments) and a standard locking mode dial.

The hot shoe sits at the center of the top plate—the camera sports a mechanical shutter for use with flash, with sync available at 1/250-second. You're limited to an external strobe, as there's no flash built into the body itself. To the left is an additional dial, a differentiating factor from the Alpha 7 II body design. It sets the Drive mode, with single, three levels of continuous speed, a self timer, and automated exposure bracketing options available. Nested into its base is a switch that changes between AF-S, AF-C, DMF, and MF focus modes.

Below the focus control, on the rear, are C3 and Menu buttons. They're nestled into the corner between the top of the LCD and to the left of the EVF eyecup. To the right of the eyepiece you'll find a dedicated Record button for video, along with AF-ON and AEL buttons, and a rear control wheel.

There's a modest thumb rest area on the rear, finished in textured rubber. The new focus joystick, a small eight-way control nub that moves the active focus area, sits between the thumb rest area and LCD. Below it is the Fn button, which launches an on-screen control menu, a flat command dial with four directional press controls and a center button, and the Play and Delete/C4 buttons. The up position is locked into adjusting what's displayed on the viewfinder and rear LCD, but the other directions can be customized.

Pressing Fn launches an on-screen control bank, arranged in two rows of six boxes at the bottom of the screen. You can customize each box to suit your liking, but you'll need to dive into the a9's menu system to do so.

Sony has long been criticized for menus that are on the confusing side. If you're unfamiliar with which items are located on which screens, you may find yourself searching through pages and pages of options just to format a memory card. After a full day of use, the a9's menu seems better organized to me, but the camera does a lot, so there's no shortage of screens.

To lessen hunting through pages of settings, there's now a My Menu option. You can place as many individual menu settings as you'd like on this page—which expands to multiple pages if you assign enough options—and you can also customize the order in which they appear. You may spend some time configuring the Alpha 9 to suit your needs, but doing so will reward you in the long run.

The 3-inch rear LCD is about the same size as you get with other full-frame Sony mirrorless cameras. But it's sharper, at 1,440k dots, and sensitive to touch. It's mounted on a hinge, and, perhaps simply to make me happy after previous gripes, Sony's engineering team has disabled the EVF eye sensor when the display isn't flush with the rear. If you're framing a shot with the LCD tilted out, you can put the camera right up to your body without the rear display going black. Earlier models were very sensitive, going dark even when holding the camera a comfortable distance away from your person.

The EVF is also an upgrade over the a7 II family. It's larger, sporting a 0.5-inch design that delivers 0.78x magnification to your eye, and sharper at 3,686k dots. It also refreshes very quickly, at your choice of 60 or 120fps. The latter is ideal for shooting fast-moving action. I won't say that I forgot I was using an EVF when shooting with the a9—the overlaid information is a reminder you're not using an optical viewfinder—but it in no way hindered my photography. In fact, coupled with the constant feed, free of blackout, I felt more in tune with the scene in front of me than I do with an SLR—it's similar to shooting with a rangefinder or TLR.

Connectivity

The a9 is the first Sony mirrorless camera to include an Ethernet port, a must for photographers working for wire agencies covering major events. You also get a PC sync socket for plugging into studio lights, 3.5mm microphone and headphone jacks, micro HDMI, and micro USB.

Sony really loves in-camera charging. Battery life in the a9 is a lot better than in past cameras—it uses a new battery with more than double the capacity of the a7 II battery. Its CIPA rating is fairly low, at 480 shots using the EVF or 650 using the LCD. But CIPA's standardized testing methodology doesn't apply to shooting at high frame rates. In one day, I shot 3,750 Raw+JPG frames and about 10 minutes of video, and was left with 35 percent on my battery—at that pace, I'd have been able to get more than 5,000 images on a single charge using a similar shooting style.

If you're using the camera professionally, you'll want to carry a backup battery with you no matter how confident you are in its ability to run all day; they cost about $80. If you invest in a few extra batteries also consider a multi-battery charger. It's a $400 accessory, but can replenish four batteries at a time.

The a9 also works with a vertical shooting grip ($350). It holds two batteries, but connects to the camera via the battery compartment so only expect double life. It also adds a vertical shutter release and additional controls (including a focus joystick).

There are two memory card slots. Slot 1, the bottom of the two, supports UHS-II SD, SDHC, and SDXC memory. Slot 2 only offers UHS-I speeds, so you can't take advantage of the fastest SD cards, but it also works with Sony's Memory Stick media. I really would have liked to see both slots support UHS-II, as swapping one card to another in the midst of shooting action is a pain, and you lose the ability to create a real-time backup of shots without sacrificing write speed.

The a9 has Wi-Fi and Bluetooth. The former is used to transfer images to your smartphone and to leverage your handset as a remote control. The latter keeps a connection alive for easier pairing, sets the camera's clock, and adds GPS data to images.

Performance and Autofocus

The a9 is all about speed. It turns on, focuses, and fires in about 1.6 seconds. Its focus system locks on in as close to no time as possible, netting an average 0.01-second in our standard stopwatch focus test. But it's in tracking fast action where the camera really excels. In our standard focus lab test, which tracks a target moving toward and away from the lens, the a9 fires off shots at 20fps and nails focus on almost every one.

Burst duration varies based on file format. If you're shooting Compressed Raw+JPG you get 225 shots at a time, with about 73.7 seconds required to clear the buffer to a Lexar 300MBps memory card. Compressed Raw capture extends the duration slightly, to 230 shots, but cuts the buffer clearing time to 67.2 seconds. JPG shooters enjoy 378 images in a burst, but it takes about 129.4 seconds to commit all of those images to memory. Of course, you can capture more images as the buffer clears.

Uncompressed Raw capture is also an option, but you only reap its full benefits when using the mechanical shutter. When you shoot Uncompressed Raw with the electronic shutter the burst rate slows to 12fps, but as with all electronic shutter images, Raw quality is 12-bit. It keeps its pace for 118 Raw+JPG and 122 Raw shots, with 53.1 and 44.2 seconds required to clear the buffer, respectively.

If you want to shoot full quality, 14-bit Raw images (in either compressed or uncompressed flavors), you'll need to use the mechanical shutter. Doing so limits the maximum burst rate to a meager 5fps. If you're not shooting fast action, and want the extra exposure latitude that a 14-bit file delivers, switching to the mechanical shutter when you're not shooting action is a wise choice. The a9 defaults to mechanical shutter when in single drive mode. You can force the camera to use either mechanical or electronic capture if desired with the C3 button, or via the menu system if you opt to assign C3 to a different function.

You sholdn't worry too much about shooting compressed files when tracking fast action. Sports photographers are often shooting in JPG in order to speed transfer of images to an editor for publication. And if you're shooting Raw with the intention of spending more time processing images, tests with other Sony cameras that offer compressed and uncompressed options have proven the differences to be quite subtle. You should expect to see some false color around bright sources of light against darker backgrounds, but it takes pretty close examination to notice.

There have been isolated reports of the a9 displaying overheating warnings during burst shooting. One photographer received a warning after 20 minutes of use at a humid swim meet, although it should be noted that the camera kept working fine. I've now shot with three separate a9 bodies in a variety of conditions, including under the bright southern California sun, and haven't been able to force the camera to overheat, even after extensive burst shooting.

The autofocus system isn't just fast, it also covers a very large area of the sensor, about 93 percent. Unlike most SLRs, that have focus systems that only cover a central area, the a9's hybrid phase and contrast detection goes almost to the very edge of the frame. No matter where your subject is placed, the a9 can lock on. It also supports Eye AF, which identifies human eyes and locks focus, a fantastic tool for keeping your subject's face in crisp focus.

I've now shot varying types of action with the a9, including equestrian events, figure skating, ice hockey, skateboarding, and track and field. In every instance, the autofocus system has passed muster with flying colors. It locks on quickly and tracks moving subjects easily. I've used a mixed of focus modes, but found that wide area or expanded flexible spot were the most useful, especially when used in conjunction with Eye AF.

From the thousands of frames I've shot with the a9—an easy figure to hit when shooting at 20fps—I only experienced one truly botched sequence. I was shooting with the wide focus area when the camera picked up the face of an approaching long jumper in the background, behind my subject. Switching to a focus setting that keeps the subject toward the middle of the frame would have sidestepped this, so I place some blame on my technique.

I'm used to employing the wide setting when shooting action with the a7 series, as changing the focus point during shooting is a pain. But the a9's focus joystick makes it very easy to move the focus area around the frame. Overall, I'm confident that the autofocus is on the same level as what you get with the EOS-1D X Mark II or Nikon D5, and in some ways—including the coverage area, burst rate, and Eye AF capability, it goes beyond what those flagship SLRs can do.

A good telephoto lens is the go-to option for covering many types of action. Sony rolled out a new lens with the a9, the FE 100-400mm F4.5-5.6 GM OSS. It fills a telephoto gap in the FE lens family, and certainly makes the entire system more appealing for pros. But if you're a photographer who uses exotic, high-end telephoto primes—like a 300mm f/2.8, 500mm f/4, or 800mm f/5.6—there's something missing. Sure, you can extend the 100-400mm with a 1.4x or 2x teleconverter, but doing so cuts into how much light the lens can gather. Lenses that long and bright are typically expensive—some more than $10,000—and Sony's run a little high as it is, but it seems like one would pair quite well with the a9.

Sony has been very agressive, rolling out new, pro-grade lenses for the FE system with regularity. I'd guess that it's only a matter of time before the we get a wide aperture telephoto prime, and in the meantime you can adapt Canon EF lenses. The best adapter we've tested, the Sigma MC-11, is in need of a firmware update to ensure full compatbility with the a9, but be aware that the a9 is limited to 10fps capture when using an adapted lens.

Image and Video Quality

The a9 sports a 24MP image sensor with a BSI design. It's similar to the BSI sensor used by the high-resolution a7R II, just with fewer pixels. It delivers very strong performance in difficult light, controlling noise and preserving detail even at high ISO settings.

Imatest tells us that the a9 keeps noise under 1.5 percent through ISO 12800. When shooting JPGs at default settings, images are crisp through ISO 6400. There's some slight blur at ISO 12800 and 25600, but I'd not hesitate to use those settings. Images at ISO 51200 take a step back in quality, and a more noticeable hit at ISO 102400. You can push the a9 to ISO 204800, which nets results that verge on blurry, but are just a little bit clearer than you get from the Nikon D5 at the same setting. If you prefer a bit more grain, but also a bit more detail, you can reduce or eliminate the amount of in-camera noise reduction applied to JPGs.

Shooting in Raw format eliminates in-camera noise reduction. Raw images deliver strong detail through ISO 25600, and while there's some grain, it isn't overwhelming or offensive. Grain is rougher at ISO 51200, but fine lines are still visible. At ISO 102400 images have a very rough appearance, and fine lines run together. Photos are rougher still at ISO 204800, maybe a little more than the Nikon D5's ISO 204800 output, but not dramatically so.

The a9's image quality at extreme ISO settings adds some reasons for a7 II owners who often cover events and weddings to consider an upgrade to the a9. You won't need to shoot at 20fps to fire off shots at a typical reception, of course, but there are certain churches and venues where flash is forbidden, and the a9 delivers cleaner high ISO images than the a7 II. The camera's ability to nab strong images in low light is further aided by its 5-axis sensor stabilization system. Any lens you attach, even a fast prime like a 35mm f/1.4 without in-lens stabilization, benefits. It's a feature you don't get in full-frame SLRs from Canon and Nikon.

The a9 shoots video at 4K quality at 24 or 30fps, with 60 or 100Mbps bit rates available. I didn't shoot a heavy amount of video, but did check to see how well the a9 tracks moving subjects when filming. It's using the same autofocus system, so in theory it should be just as good as still, but I did see some moving in and out of focus during fast motion, as you can see with the shot of the figure skater in our sample video.

If you opt for 1080p, the top frame rate improves to 120fps. That's a big plus if you're into slow-motion capture. I shot some long jumpers at 120fps and slowed the footage down for 30fps playback—one-quarter speed. Autofocus is quite strong here, just as good as it is for 4K capture. If I have a complaint about the video options, it's that you must wait for stills to commit to memory before starting a video. The shooting buffer is huge, so if you fill it up you'll have to wait a while, sometimes upward of two minutes, to start recording a video.

Conclusions

The Sony a9 is a big step forward for mirrorless technology. It betters the fastest, most expensive SLRs in capture rate, spreads its autofocus system across almost the entirety of a full-fame image sensor, and has a really fantastic EVF—one that, in many ways, is a better option for shooting action than an optical finder. It's also significantly smaller and lighter than a top-end Canon or Nikon, and less expensive—although that advantage is lessened by the need to buy some extra batteries and a charger, lenses that trend a bit higher in cost, and a lack of strong third-party lens support.

The camera's best attribute isn't its burst speed alone. The complete lack of blackout when capturing images changes the way you can capture quick-moving subjects. If a basketball player makes a sudden juke in an unexpected direction, you'll be able to better follow them with your lens. Likewise, if you're trying to grab a shot of erratic fauna, like a swallow in flight, the camera can better keep up with their movements, even when using a lens long enough to keep them tightly framed. And because the autofocus system covers so much of the image sensor area, you don't have to worry about your subject moving outside of the range of autofocus.

The a9 stands alone in its class in the mirrorless world—nothing else has as big of a sensor or shoots so quickly. If you're invested in the system and have been patiently waiting for a camera like this, your patience has been rewarded. The a9 is a reminder that mirorrless cameras have come a long way, and in some ways have moved beyond what even the highest-grade SLRs can accomplish. It may not be enough to sway Canon and Nikon owners with years of muscle memory and deep investments in hardware away from their chosen system, but it's a clear sign that Sony has every intention of remaining a very serious player in the professional photography space.

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About the Author

Senior digital camera analyst for the PCMag consumer electronics reviews team, Jim Fisher is a graduate of the Rensselaer Polytechnic Institute, where he concentrated on documentary video production. Jim's interest in photography really took off when he borrowed his father's Hasselblad 500C and light meter in 2007. He honed his writing skills at re... See Full Bio

Sony a9

Sony a9

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